The present invention relates to a semiconductor device manufacturing method, and particularly to a semiconductor device manufacturing method of selectively or entirely etching an insulating film on the surface of a silicon semiconductor to entirely or selectively expose the surface of the silicon semiconductor, and then forming a thin film so as to cover at least the etched portion.
In order to establish the contact between a silicon semiconductor substrate or a patterned polysilicon semiconductor layer and other conductive layers in manufacturing of a silicon-based semiconductor device, there is passed a process of forming an interlayer insulating film before the other conductive layers are formed, then selectively etching a portion of the interlayer insulating film at which the contact is established (a photoresist film is selectively formed, and then a wet etching treatment is performed by using the film as a mask), thereby removing the portion and forming an opening, and then forming other conductive films (polysilicon film, silicide film, metal film) (the film is entirely formed by the Chemical Vapor Deposition (CVD), sputtering or the like, and then a photoetching treatment is performed).
When an MIS capacitor is formed, the insulating film on the surface of the semiconductor substrate in which each semiconductor region is formed is selectively etched to form an opening, and then an insulating film formed of silicon nitride Si.sub.3 N.sub.4 which constitutes dielectric substance.
However, there is the problem that when the interlayer insulating film on the silicon semiconductor substrate or the patterned polysilicon semiconductor layer is etched to form an opening and expose the surface of the semiconductor substrate or the semiconductor layer, the surface of the opening portion is naturally oxidized from that time until the conductive layer or the insulating film constituting the dielectric substance is formed. The natural oxidation occurs due to cleaning in a solution treatment or when it is left in the air.
The natural oxidation increases the contact resistance, and causes dispersion, and thus this is inconvenient. In the case of a washed polysilicon emitter transistor, it causes dispersion in characteristics such as current amplification, frequency characteristic, etc. of the transistor, and this is inconvenient. In the case of MIS (Metal Insulator Semiconductor) capacitor, it reduces the capacitance value and causes the dispersion, and thus this is inconvenient.
In the case of the MIS capacitor, the parasitic capacitance due to a natural oxidation film serves as in-series capacitance to the original capacitance. The design of the insulating film formed of silicon nitride or the like which constitutes dielectric substance is directed to the thin film design due to shrinkage of IC which will be further severer in the future, and thus the degree of variation of the capacitance due to the natural oxidation film is increased more and more, so that this problem is extremely important.
Therefore, the inventor of this application has made various experiments, and consequently he has found out that a silicon carbide SixCy (hereinafter merely referred to as "SiC") film which is a composition of silicon and carbon (carbon) C has a function of prohibiting formation of the natural oxidation film. Therefore, he has groped to effectively use the SiC film in order to prohibit the natural oxidation film, and has implemented the present invention.